Trajectories of body mass index amongst children who develop type 2 diabetes as adults

Type 2 diabetes (T2D) is a heterogeneous disorder. The aim of this study was to examine the trajectories of childhood growth associated with T2D.

A total of 13 345 individuals born in Helsinki, Finland between 1934 and 1944 were included in the study. The participants' growth had been recorded in detail during childhood, and 11.7% (n = 1558) had been diagnosed with T2D. We divided the cohort around the median body mass index (BMI) at 11 years. Body composition and glucose tolerance were assessed in a clinical subsample (n = 2003) in adulthood.

Two pathways of growth were associated with T2D. Both began with low weight and BMI at birth. In one, persistent low BMI through infancy was followed by a rapid increase in BMI in childhood. Amongst individuals with a BMI at 11 years above the median value, the odds ratio for T2D associated with a one z-score increase in BMI between 2 and 11 years was 1.31 (95% confidence interval 1.21-1.42, P < 0.001). In the other pathway, low BMI at birth, accompanied by short length at birth, was followed by low BMI in childhood. Most women who developed diabetes followed this trajectory; they developed T2D at a lower BMI and lower fat percentage than women with a BMI above the median at 11 years of age.

Two pathways of early growth trigger T2D. Low fat deposition leading to thinness at birth and during infancy results in fat acquisition during childhood. Reduced linear growth leading to short length at birth is associated with lower body fat percentage in adulthood but increased risk of developing diabetes.